This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Our studies focus on understanding the structural bases for divergent evolution in groups of homologous enzymes that catalyze different reactions. We are interested in the enolase superfamily, a group of mechanistically diverse enzymes that share enolization of a carboxylate anion substrate, and the orotidine 5-monophosphate (OMPDC) suprafamily, a group of functionally distinct enzymes that share no discernible mechanistic attributes, and D-ribulose 1,5-bisphosphate carboxylase/oxygenase superfamily. All three homologous groups of enzymes share the (b/a)8-fold, the most commonly observed fold in structurally characterized enzymes. At present we are using Chimera to visualize and superimpose structures of members of all three homologous groups. We also use the SFLD to assist with our bioinformatic analyses.